condition mean min max ZT0-3 19.250806 19.250806 19.250806 ZT4-7 17.0308715 17.0308715 17.0308715 ZT8-11 15.942034499999998 15.942034499999998 15.942034499999998 ZT12-15 17.870260000000002 17.870260000000002 17.870260000000002 ZT16-19 17.674568999999998 17.674568999999998 17.674568999999998 ZT20-23 18.3345445 18.3345445 18.3345445